feat: integrate rclone WebDAV backup for PC-to-PC file sync

Source PC serves backups/ folder via rclone WebDAV server (auto-starts with app).
Receiver PC pulls backups on schedule using rclone sync.
Network Backup UI now has two tabs: Rclone and API Key.
Rclone installed automatically via postinstall script.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/Backend/src/services/rcloneConfigService.ts

@@ -0,0 +1,50 @@
+import fs from "fs";
+import path from "path";
+
+const CONFIG_FILE = path.resolve(process.cwd(), "rclone-config.json");
+
+export const RCLONE_USER = "MyDentalApp";
+export const RCLONE_PASS = "SuperSecret!@2026";
+
+export interface RcloneConfig {
+  // Source role: serve backups folder via WebDAV
+  serverEnabled: boolean;
+  serverPort: number;
+
+  // Receiver role: pull backups from source PC
+  receiverEnabled: boolean;
+  receiverSyncHour: number;
+  sourceIp: string;
+  sourcePort: number;
+  lastSyncAt: string | null;
+  lastSyncStatus: string | null;
+  lastSyncError: string | null;
+}
+
+const DEFAULT_CONFIG: RcloneConfig = {
+  serverEnabled: false,
+  serverPort: 8080,
+  receiverEnabled: false,
+  receiverSyncHour: 21,
+  sourceIp: "",
+  sourcePort: 8080,
+  lastSyncAt: null,
+  lastSyncStatus: null,
+  lastSyncError: null,
+};
+
+export function readRcloneConfig(): RcloneConfig {
+  if (fs.existsSync(CONFIG_FILE)) {
+    try {
+      return { ...DEFAULT_CONFIG, ...JSON.parse(fs.readFileSync(CONFIG_FILE, "utf8")) };
+    } catch {}
+  }
+  return { ...DEFAULT_CONFIG };
+}
+
+export function writeRcloneConfig(patch: Partial<RcloneConfig>): RcloneConfig {
+  const current = readRcloneConfig();
+  const updated = { ...current, ...patch };
+  fs.writeFileSync(CONFIG_FILE, JSON.stringify(updated, null, 2), "utf8");
+  return updated;
+}